Upgrade Your Vintage Mustang Audio Four Channel Amplifier

13. Brand new and not even on RetroSound’s website at the time of this writing is its plug-in 45 watts-per-channel four-channel amplifier. With no special wiring required other than providing the unit power and ground, the unit interfaces with the Model Two’s wiring connectors directly (shown at the bottom of this photo) for speaker in/out connections, amp turn on, and more, making it a compact and easy to hide solution for upping the output of your stereo.